I definitely noticed more fuel after I did the FCA mod. Settings that didn't smoke before started smoking, despite the fact that I increased my turbo boost at the same time. It was worth doing. That was with stock injectors.
I recently did the CP3 gear plate mod and a T&C wild fuel rail in conjunction with Flux 1 injectors and a rail pressure gauge. This combo can keep up with an Edge Juice on 5, but not with the Hot Juice. When my bank account recovers from this last round of mods I'll be going with a professionally modded CP3 pump -- probably a Floor-it Stage 2. I just don't see a need for twin CP3's with the relatively small injectors I'm using to control smoke.
Other than the fact that my tires keep breaking loose, there haven't been any driveability or noise issues with the mods I've done so far.